The present invention relates to bioprosthetics and particularly to the use of bioprosthetics for the repair and replacement of connective tissue. More particularly, the present invention relates to the use of a composite bioprosthetic device made up of a synthetic portion and heterologous animal tissue.
Currently there are multiple patents and publications that describe in detail the characteristics and properties of small intestine submucosa (SIS). See, for example, U.S. Pat. Nos. 4,352,463, 4,902,508, 4,956,178, 5,281,422, 5,372,821, 5,445,833, 5,516,533, 5,573,784, 5,641,518, 5,645,860, 5,668,288, 5,695,998, 5,711,969, 5,730,933, 5,733,868, 5,753,267, 5,755,791, 5,762,966, 5,788,625, 5,866,414, 5,885,619, 5,922,028, 6,056,777, and WO 97/37613, incorporated herein by reference. SIS, in various forms, is commercially available from Cook Biotech Incorporated (Bloomington, Ind.). Further, U.S. Pat. No. 4,400,833 to Kurland and PCT publication having International Publication Number WO 00/16822 provide information related to bioprosthetics and are also incorporated herein by reference.
There are currently many ways in which various types of soft tissues such as ligaments or tendons, for example, are reinforced and/or reconstructed. Suturing the torn or ruptured ends of the tissue is one method of attempting to restore function to the injured tissue. Sutures may also be reinforced through the use of synthetic non-bioabsorbable or bioabsorbable materials. Autografting, where tissue is taken from another site on the patient""s body, is another means of soft tissue reconstruction. Yet another means of repair or reconstruction can be achieved through allografting, where tissue from a donor of the same species is used. Still another means of repair or reconstruction of soft tissue is through xenografting in which tissue from a donor of a different species is used.
According to the present invention, a bioprosthetic device for soft tissue attachment, reinforcement, and/or reconstruction is provided. The bioprosthetic device comprises a small intestinal submucosa (SIS) or other naturally occurring extracellular matrix (ECM), formed to include a tissue layer of SIS, and a synthetic portion coupled to the SIS tissue layer. The tissue layer of SIS may also be dehydrated.
In preferred embodiments, the SIS portion of the bioprosthetic device includes a top tissue layer of SIS material and a bottom tissue layer of SIS material coupled to the top tissue layer. The synthetic portion of the bioprosthetic device includes a row of fibers positioned to lie between the top and bottom tissue layers of the SIS portion. The fibers are positioned to lie in a spaced-apart coplanar relation to one another along a length, L, of the SIS portion. The fibers are each formed to include a length L2, where L2 is longer than L so that an outer end portion of each fiber extends beyond the SIS portion in order to anchor the bioprosthetic device to the surrounding soft tissue.
In other embodiments, the synthetic portion of the bioprosthetic device includes a mesh member formed to define the same length, L, as the SIS portion. In yet another embodiment, the synthetic portion of the bioprosthetic device includes a mesh member having a body portion coupled to the SIS portion and outer wing members coupled to the body portion and positioned to extend beyond the length, L, and a width, W, of the SIS portion in order to provide more material for anchoring the bioprosthetic device to the surrounding soft tissue.
SIS is intended to identify small intestine submucosa. While porcine SIS is widely used, it will be appreciated that small intestine submucosa may be obtained from other animal sources, including cattle, sheep, and other warm-blooded mammals. Further, other sources of extracellular matrices from various tissues are known to be effective for tissue remodeling as well. These sources include, but are not limited to, stomach, bladder, alimentary, respiratory, and genital submucosa. See, e.g., U.S. Pat. Nos. 6,171,344, 6,099,567, and 5,554,389, hereby incorporated by reference. Such submucosa-derived matrices comprise highly conserved collagens, glycoproteins, proteoglycans, and glycosaminoglycans. Additionally, other ECMs are known, for example lamina propria and stratum compactum.
For the purposes of this invention, it is within the definition of a naturally occurring ECM to clean, delaminate, and/or comminute the ECM, or even to cross-link the collagen fibers within the ECM. However, it is not within the definition of a naturally occurring ECM to extract and purify the natural fibers and refabricate a matrix material from purified natural fibers. Compare WO 00/16822 A1. Thus, while reference is made to SIS, it is understood that other naturally occurring ECMs are within the scope of this invention.
Fiber is intended to identify a synthetic reinforcement component present within the implant to contribute enhanced mechanical and handling properties. The reinforcement component is preferably in the form of a braided suture or a mesh fabric that is biocompatible. The reinforcement component may be bioabsorbable as well.
The reinforcing component of the tissue implant of the present invention may be comprised of any absorbable or non-absorbable biocompatible material, including textiles with woven, knitted, warped knitted (i.e., lace-like), non-woven, and braided structures. In an exemplary embodiment the reinforcing component has a mesh-like structure. In any of the above structures, mechanical properties of the material can be altered by changing the density or texture of the material. The fibers used to make the reinforcing component can be, for example, monofilaments, yarns, threads, braids, or bundles of fibers. These fibers can be made of any biocompatible material, including bioabsorbable materials such as polylactic acid (PLA), polyglycolic acid (PGA), polycaprolactone (PCL), polydioxanone (PDO), trimethylene carbonate (TMC), polyvinyl alcohol (PVA), and copolymers or blends thereof. In an exemplary embodiment, the fibers that comprise the mesh are formed of a polylactic acid and polyglycolic acid copolymer at a 95:5 mole ratio.
Additional features of the present invention will become apparent to those skilled in the art upon consideration of the following description of preferred embodiments of the invention exemplifying the best mode of carrying out the invention as presently perceived.